Premium
Effect of Membrane Polyunsaturation on Carrier‐Mediated Transport in Cultured Retinoblastoma Cells: Alterations in Taurine Uptake
Author(s) -
Yorek Mark A.,
Strom David K.,
Spector Arthur A.
Publication year - 1984
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1984.tb09726.x
Subject(s) - taurine , biochemistry , polyunsaturated fatty acid , biology , arachidonic acid , fatty acid , membrane transport , amino acid , serine , chemistry , membrane , enzyme
Summary: Neural cell membranes naturally contain a large amount of polyunsaturated fatty acid, but the functional significance of this is unknown. An increase in membrane polyunsaturation has been shown previously to affect the high‐affinity transport systems for choline and glycine in cultured human Y79 retinoblastoma cells. To test the generality of membrane polyunsaturation effects on transport, we investigated the uptake of other putative neurotransmitters and amino acids by these cells. Taurine, glutamate, and leucine were taken up by both high‐ and low‐affinity transport systems, whereas serine, γ‐aminobutyrate, and α‐aminoisobutyrate were taken up only by low‐affinity systems. The high‐affinity taurine and glutamate and low‐affinity serine uptake systems were Na + dependent. Arachidonic acid (20:4) supplementation of Y79 cells produced enrichment of all the major microsomal phosphoglycerides with 20:4, while docosahexaenoic acid (22:6) supplementation produced large increases in the 22:6 content of all fractions except the inositol phosphoglycerides. Enrichment with these polyunsaturated fatty acids facilitated taurine uptake by lowering the K ′ of its high‐affinity transport system. By contrast, enrichment with oleic acid did not affect taurine uptake. Glutamate, leucine, serine, γ‐aminobutyrate, and α‐aminoisobutyrate uptake were not affected when the cells were enriched with any of these fatty acids. These findings demonstrate that only certain transport systems are sensitive to the polyunsaturated fatty acid content of the retinoblastoma cell membrane. The various transport systems either respond differently to changes in membrane lipid unsaturation, or they are located in lipid domains that are modified to different extents by changes in unsaturation.